Reference or Value Semantics for Graph Traversal Range

[Steven Schveighoffer via Digitalmars-d-learn]

On 2/18/15 8:59 AM, "Nordlöw" wrote:
> On Wednesday, 18 February 2015 at 13:53:17 UTC, Tobias Pankrath wrote:
>>> All the data members except distMap have reference semantics.
>>
>> I thought AAs had reference semantics.
>
> Me too, but the indeed have value semantics. See for example:
>
> unittest
> {
>      string[int] x;
>      auto y = x;
>      x[0] = "zero";
>      assert(x != y);
> }

This is a well known problem.

An UNINITIALIZED AA has not yet been allocated, and so it's reference is 
null.

But once initialized, it DOES have reference semantics:

string[int] x;
x[0] = "zero";
auto y = x;
x[1] = "one";
assert(x == y);

And to anticipate your question, no there is no way (yet) to create an 
empty but initialized AA.

-Steve